A novel diamine (3,6-CAPDA) bearing carbazole and amide group was prepared. On the basis of 3,6-CAPDA and pyromellitic dianhydride (PMDA), a high-barrier polyimide (3,6-CAPPI) was obtained through a two-step polymerization method. The 3,6-CAPPI displays excellent barrier performances and thermal stability. Its oxygen permeability (OP) and water vapor permeability (WVP) are low to 2.63 cm³·mil·m⁻²·day⁻¹ and 3.22 g·mil·m⁻²·day⁻¹, respectively. The 5% weight-loss temperature (T_d5%) and glass transition temperature (T_g) are up to 526 °C and 431 °C, respectively. Through a combination of molecular simulation, X-ray diffraction and positron annihilation test, the effet of polymer structure on the barrier properties are fully explored. The results demonstrate that the introduction of carbazole and amide groups not only improves the chain order and rigidity, but also enhances the interchain force of polyimide, which thereby bring about enhancement of crystallinity and decreases of free volume and chain movement of 3,6-CAPPI. These factors lower the gas diffusivity and solubility in polymer matrix. Simultaneous decreases of gas diffusivity and solubility give rise to the notable enhancement of gas barrier for 3,6-CAPPI.

制备了带有咔唑和酰胺基的新型二胺（3,6-CAPDA）。在3,6-CAPDA和均苯四甲酸二酐（PMDA）的基础上，通过两步聚合方法获得了高阻隔性聚酰亚胺（3,6-CAPPI）。3,6-CAPPI具有出色的阻隔性能和热稳定性。其氧渗透率（OP）和水蒸气渗透率（WVP）分别低至2.63cm ³ ·mil·m ^-2 ·day ^-1和3.22g·mil·m ^-2 ·day ^-1。5％的失重温度（T _d5％）和玻璃化转变温度（T _g）分别高达526°C和431°C。通过分子模拟，X射线衍射和正电子an灭试验的结合，充分探索了聚合物结构对阻隔性能的影响。结果表明，咔唑基和酰胺基的引入不仅改善了链的顺序和刚性，而且增强了聚酰亚胺的链间作用力，从而提高了结晶度，并降低了3,6-CAPPI的自由体积和链运动。 。这些因素降低了气体在聚合物基质中的扩散性和溶解性。气体扩散率和溶解度的同时降低导致3,6-CAPPI气体阻隔性显着提高。